Many modern electronic devices have been adapted for portable use by miniaturizing the electronic components and by providing a battery power source. Examples include laptop computers, "Walkman".RTM. type tape and compact disk players, and cellular phones. The use of these devices may be limited, however, by the life of the battery power source. Accordingly, there have been attempts in the art to reduce the inconvenience resulting from the need to change batteries.
The use of an external battery with a portable notebook type computer is disclosed in U.S. Pat. No. 5,200,685 to Sakamoto entitled "Adapter For External Battery and Battery System." In this patent, the internal battery may be removed while power is supplied from the external battery. Accordingly, the internal batteries may be exchanged while the external battery is connected to the personal computer. This operation may require, however, that extra internal batteries as well as the external battery be carried.
Another approach is disclosed in U.S. Pat. No. 5,036,532 to Metroka et el. entitled "Portable Telephone With Power Source/Mode Change During Calls." This patent discloses a cellular portable telephone that accommodates a power source change between the portable's battery and another battery during a cellular telephone call. If another battery is plugged into the cellular telephone within four seconds after the first battery is removed, the telephone may re-enter the cellular telephone call that was in process when the discharged battery was removed. If the charged battery is not plugged into the telephone within the four second time period, however, the previous cellular telephone call will not be reentered. Accordingly, quick action may be required in order to change batteries during a call without interrupting the call.
Notwithstanding the above mentioned references, there exists a need in the art for an apparatus and method for changing a nearly discharged battery in a portable electronic device without interrupting service of the device. In particular, there exists a need for an apparatus and method for changing the battery of a cellular telephone during a call without interrupting the call or requiring quick action.